Today, we put the latest version of our sour IPA, Empress, on tap. Each time we’ve made this beer, we use a different fruit. This version used a huge amount of fresh pineapple. Feedback on the beer has been really good, so I’d like to take a minute and discuss this difficult style and what I think is the best way to do it.

First, what is a sour IPA? There are various examples, but I believe that a sour IPA is a beer that exhibits both sourness and IPA qualities–some hop bitterness, and a firm dry hop. A sour IPA is not just a dry-hopped sour. That style has been done really well, but it is different, because a sour IPA also has some bitterness, and that is a key difference.

Sour and bitter don’t go together. You may have heard this before, as well as some of the reasoning: in nature, bitter and sour together indicate a poisonous substance. Whatever the reasons, most people do not like the combination.

Since that’s the case, how do you make a beer that exhibits both? Here’s the recipe for Empress:

OG: 15 P

17 calculated IBU

70% pilsner

30% flaked wheat

8 oz per BBL Simcoe @ whirlpool

8 oz per BBL Mosaic @ whirlpool

12 oz per BBL Simcoe dry hop, added during fermentation

12 oz per BBL Mosaic dry hop, added during fermentation

Bring wort to a boil, cool to 90 degrees. Add a healthy starter of lactobacillus plantarum. Allow beer to reach 3.4 PH. Bring to a boil. Proceed with flameout hops. Ferment out with 1318 or S-04 yeast. Add dry hops during fermentation.

So, the key element of this beer is the low IBU. Some people believe a 17 IBU beer cannot be called an IPA, but I can attest that this beer is plenty bitter. In fact, the base beer without fruit is too bitter for me, although some people enjoy it.

Most importantly, this is only calculated IBU. I have no idea what the actual IBUs are, since we have not gotten this beer tested yet, but we plan to, since I want to add this to the offerings at our big place. Furthermore, recent research suggests that dry hopping does add to IBUs, so the big dry hop could definitely contribute.

So for this beer, in order to get the balance right, we need to assume that increased bitterness increases perceived sourness, and vice versa. So despite the low IBUs, this beer tastes bitter and fairly sour.

I have tasted some examples and made a sour IPA with higher IBUs. I did not enjoy any of them, and I have no problem drinking a 100 IBU IPA. I think this delicate balance is key. A local brewery makes a really good Berliner that is 13 IBU, and tastes far more sour than I have ever been able to achieve with plantarum and 0 IBU. But it doesn’t taste bitter. Why? The bitterness is exactly enough to tilt the balance in favor of the lactic acid.

I am really excited to bring this style to more people. When I left the tasting room tonight, this beer was all anyone was drinking. It’s a tough beer to pull off, but the results are worth it.